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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        /*
            基本：number,string,boolean,undefined,null 
            typeof number string boolean undefined object

            引用:对象、数组、函数。
        */
        let a = 12.33 ; 
        console.log(typeof a);
        let b =`helloworld`;
        console.log(typeof b);
        let c = true ; 
        console.log(typeof c);

        let d;
        console.log(d,(typeof d));
        //javascript设计的时候借鉴了java
        let e =null ;
        console.log(e,typeof e);
        console.clear();
        //创建了一个对象
        let obj = new Object();
        console.log(obj);
        console.log(typeof obj);
        //创建一个日期对象
        let date = new Date();
        console.log(date);
        console.log(typeof date);
        console.clear();
        let arr = new Array();
        console.log(arr);
        console.log(typeof arr)
    </script>
</body>
</html>